Valve guide reaming results

[Plummit]

Originally Posted by Mconner7

For those that didn’t follow my entire saga, I had #3 valve stick on my O-540 and bent the pushrod. When I dropped the exhaust valve I found spalling of the guide that is in the first picture.

I reamed the guide but was not happy with the results so I pulled the cylinder and on close inspection found spalled lifters and worn cam lobes. I am sure this /is the source of the hard foreign materiel that made its way into the valve guide and stuck the valve.

Time for a tear down with less than 800 SMOH.

How were your oil changes/filter exams? Any metal?

-Marc

[RV8JD]

Originally Posted by Mconner7

For those that didn’t follow my entire saga, I had #3 valve stick on my O-540 and bent the pushrod. When I dropped the exhaust valve I found spalling of the guide that is in the first picture.

I reamed the guide but was not happy with the results so I pulled the cylinder and on close inspection found spalled lifters and worn cam lobes. I am sure this is the source of the hard foreign materiel that made its way into the valve guide and stuck the valve.

Time for a tear down with less than 800 SMOH.

Thanks for sharing the results you found.

[lr172]

Originally Posted by hgerhardt

That gray slurry is probably the broken-down abrasive from the ball hone. The abrasive has to break down during use so as to uncover fresh abrasive as it's working.

+1

It is also being thinned and mixed with the ATF in your case, which will bring it more towards gray. No need for reamers with lead. It doesn't really stick to anything.

[lr172]

Originally Posted by Steve Watkins

I had #3 exhaust valve completely stick open on friday afternoon. Luckily I was 8,500' and about 8 miles from an airport. It never gave any indication of a problem until it completely failed. Factory Lycoming IO-360M1B from Vans with 930 hrs total. Cylinder is in the shop for a guide replacement and possibly new valve. Bent the pushrod. No piston damage. #3 has always run a little bit leaner that the others and I was in the process of running the Airflow Performance nozzle tuning test when it failed. I typically cruise at 65% power lean of peak. 1, 2, and 4 run about 25 degrees lop and 3 is closer to 80 lop. Engine shop says #3 is much more common to have a stuck valve that the others.

#3 is where the head is getting less cooling due to the limited fin depth. More evidence that it is too much heat and not too little.

Curious if you took steps to increase airflow behind #3.

Larry

[Steve Watkins]

Curious if you took steps to increase airflow behind #3.

Does this apply to the parallel valve motors, or just the angle valve? #3 on my engine runs only a few degrees hotter than the others in climb and about 20 degrees cooler in cruise as it is further lean of peak than the other 3. Never exceeds 400F in climb and cruise is about 340-350F. I was in the process of gathering gami spread data to tune the injector nozzles when the failure occurred.

[Gusmax]

That is bad news Mconner7!!

Do you know how many years it has been since overhaul?

[Canadian_JOY]

Originally Posted by lr172

+1

It is also being thinned and mixed with the ATF in your case, which will bring it more towards gray. No need for reamers with lead. It doesn't really stick to anything.

Ummm... from your comment I would suspect you don't shoot very much pistol with lead bullets. Getting the lead removed from chambers, forcing cones and barrels is a tough enough challenge that most experienced shooters might argue the point about the "stickiness" of lead.

Add pressure and heat and lead forms a smooth shiny surface that looks like polished steel.

I hadn't thought of the color of the penetrating oil as a factor - thanks for helping to get my thinking pointed in the right direction.

[lr172]

Originally Posted by Canadian_JOY

Ummm... from your comment I would suspect you don't shoot very much pistol with lead bullets. Getting the lead removed from chambers, forcing cones and barrels is a tough enough challenge that most experienced shooters might argue the point about the "stickiness" of lead.

Add pressure and heat and lead forms a smooth shiny surface that looks like polished steel.

I hadn't thought of the color of the penetrating oil as a factor - thanks for helping to get my thinking pointed in the right direction.

You are correct. Very little experience cleaning hand guns. I suspect that some of the challenge is that the rifling grooves create a mechanical bond for the lead. I do know that very thin lead deposits stick well to steel when high heat is a applied. Prior to the mid 70's this is the process used to protect valve faces and seats. Once they took the lead out of gas, new alloys had to be used to prevent wear and many older engines lost compression as the valve parts beat themselves to death without the lead coating.

Larry

[Mconner7]

Originally Posted by Gusmax

That is bad news Mconner7!!

Do you know how many years it has been since overhaul?

Around 10 years since overhaul. It was in Phoenix the first 6 years but my hangar is a stones throw from Tampa Bay.

I am blaming the tappet corrosion on salt air and a couple of 6-8 week down times due to the pandemic. I switched from Aeroshell 100+ to Phillips and Camguard a year ago. I will use Camguard from now on regardless of oil because of the salty air at home.